All industrial operations produce some wastewater which must be returned to the environment. Wastewater treatment is directed toward removal of pollutants with the least effort. Suspended solids are removed by either physical or chemical separation techniques and handled as concentrated solids (sludge). Current physical methods of cleaning wastewater streams rely on gravity separation, CPI (corrugated plate interceptor) systems for example, multiple rake and paddle arrangements such as found in API separators, hydrocyclones and pumps to remove settleable solids and oil. Solid-laden sludge tends to build up and damage equipment in these primary treatment systems. Many of these systems are typically below ground so maintenance is difficult and repairs costly.
Various equipment and systems are known to separate mixtures of solid, oil and water into divergent streams. Vegner, et al., U.S. Pat. No. 2,754,968, disclose the treatment of liquid materials with plural hydrocyclones in series. An apparatus is disclosed that is comprised of first, second and third hydrocyclones, closed communication means between the vortex finder of the first hydrocyclone and the feed entrance of the second hydrocyclone and closed communication means between the apex aperture of the first hydrocyclone and the feed entrance of the third hydrocyclone. Given, et al., U.S. Pat. No. 3,338,814, disclose plural cyclones in parallel to separate solids from liquids. Specifically, '814 discloses the separation of oil from bituminous emulsions containing appreciable quantities of mineral solids. Two-stage cycloning is disclosed for separation of mineral solids encompassing a large range of particle size. Given discusses that if arranged by subsequent processing, greater amounts of solids can be removed to leave less solids in the overflow stream.
Darley, et al., U.S. Pat. No. 3,764,008, disclose a process for recovering oil from produced sand. The well operating process treats fluid produced from a sand productive hydrocarbon recovery well in order to isolate marketable hydrocarbons, a substantially oil-free water and a substantially oil-free sand. Unabsorbed hydrocarbons are removed, sand is partially de-oiled by entraining it in a stream of relatively high speed jet of water, centrifugally separating the resultant sand laden water stream by removing an oily water overflow and a sandy water underflow, and removing the oil from the oily water. In the process, clean water is recycled back into the treatment system.
A method and apparatus for cleaning chemical-containing water solutions to remove impurities from the solution so that the solution can be reused is disclosed in Inskeep, U.S. Pat. No. 4,571,301. The dirty solution is collected in a reservoir and the solution is pumped from the reservoir to a cyclone separator. A conduit from the reservoir to cyclone separator includes a screen for removal of leaves, gravel, etc. The contents of reservoir are screened and pumped into cyclone separator. Underflow from cyclone separator enters a container wherein solids settle out and liquid overflows into pipe and recycle back to reservoir.
Shaw et al., U.S. Pat. No. 5,350,525, disclose a system and process for hydrocyclone separation of particulate solids and at least one liquid phase from a multiphase liquid mixture. The use of a three phase gravity separator is indicated. The fluid in the water leg from the gravity separator is a multiphase liquid and is directed first to a solid/liquid hydrocyclone and than delivered to a liquid/liquid hydrocyclone for separating the liquid stream into a heavier liquid phase and a lighter liquid phase. The gravity separator is the primary separation device.
None of the prior teachings adequately addressed or solved the problem of intercepting and removing a majority of wastewater solids prior to the wastewater entering primary treatment systems to prevent costly damage to expensive equipment.